METOPROLOL TARTRATE

Metoprolol tartrate is a selective beta 1 -adrenoreceptor blocking agent, available as 25 mg, 37.5 mg, 50 mg, 75 mg and 100 mg tablets for oral administration. Metoprolol tartrate is (±)-1-(isopropylamino)-3-[ p -2-methoxyethyl)phenoxy]-2-propanol (2:1) dextro -tartrate salt. Its structural formula is: Metoprolol tartrate, USP is a white, crystalline powder with a molecular weight of 684.82. It is very soluble in water; freely soluble in methylene chloride, in chloroform, and in alcohol; slightly soluble in acetone; and insoluble in ether. Each tablet for oral administration contains 25 mg, 37.5 mg, 50 mg, 75 mg or 100 mg of metoprolol tartrate and the following inactive ingredients: lactose monohydrate, colloidal silicon dioxide, hypromellose, magnesium stearate, microcrystalline cellulose, polyethylene glycol, titanium dioxide, sodium starch glycolate, talc and D & C Red #30 Aluminium Lake. Chemical Structure

Hypertension Metoprolol tartrate tablets are indicated for the treatment of hypertension. They may be used alone or in combination with other antihypertensive agents. Angina Pectoris Metoprolol tartrate tablets are indicated in the long-term treatment of angina pectoris. Myocardial Infarction Metoprolol tartrate tablets are indicated in the treatment of hemodynamically stable patients with definite or suspected acute myocardial infarction to reduce cardiovascular mortality when used alone or in conjunction with intravenous metoprolol. Oral Metoprolol tartrate tablets therapy can be initiated after intravenous metoprolol therapy or, alternatively, oral treatment can begin within 3 to 10 days of the acute event. (See DOSAGE AND ADMINISTRATION , CONTRAINDICATIONS , and WARNINGS ).

Hypertension Individualize the dosage of metoprolol tartrate tablets. Metoprolol tartrate tablets should be taken with or immediately following meals. The usual initial dosage of metoprolol tartrate tablets is 100 mg daily in single or divided doses, whether used alone or added to a diuretic. Increase the dosage at weekly (or longer) intervals until optimum blood pressure reduction is achieved. In general, the maximum effect of any given dosage level will be apparent after one week of therapy. The effective dosage range of metoprolol tartrate tablets is 100 mg per day to 450 mg per day. Dosages above 450 mg per day have not been studied. While once daily dosing is effective and can maintain a reduction in blood pressure throughout the day, lower doses (especially 100 mg) may not maintain a full effect at the end of the 24-hour period, and larger or more frequent daily doses may be required. This can be evaluated by measuring blood pressure near the end of the dosing interval to determine whether satisfactory control is being maintained throughout the day. Beta 1 selectivity diminishes as the dose of Metoprolol is increased. Angina Pectoris The dosage of metoprolol tartrate tablets should be individualized. Metoprolol tartrate tablets should be taken with or immediately following meals. The usual initial dosage of metoprolol tartrate tablets is 100 mg daily, given in two divided doses. Gradually increase the dosage at weekly intervals until optimum clinical response has been obtained or there is pronounced slowing of the heart rate. The effective dosage range of metoprolol tartrate tablets is 100 mg per day to 450 mg per day. Dosages above 400 mg per day have not been studied. If treatment is to be discontinued, gradually decrease the dosage over a period of 1 to 2 weeks (see WARNINGS ). Myocardial Infarction Early Treatment During the early phase of definite or suspected acute myocardial infarction, initiate treatment with metoprolol tartrate tablets as soon as possible after the patient’s arrival in the hospital. Such treatment should be initiated in a coronary care or similar unit immediately after the patient’s hemodynamic condition has stabilized. Begin treatment in this early phase with the intravenous administration of three bolus injections of 5 mg of metoprolol tartrate each; give the injections at approximately 2 minute intervals. During the intravenous administration of metoprolol, monitor blood pressure, heart rate, and electrocardiogram. In patients who tolerate the full intravenous dose (15 mg), initiate metoprolol tartrate tablets, 50 mg every 6 hours, 15 minutes after the last intravenous dose and continue for 48 hours. Thereafter, the maintenance dosage is 100 mg twice daily (see Late Treatment below). Start patients who appear not to tolerate the full intravenous dose on metoprolol tartrate tablets either 25 mg or 50 mg every 6 hours (depending on the degree of intolerance) 15 minutes after the last intravenous dose or as soon as their clinical condition allows. In patients with severe intolerance, discontinue metoprolol tartrate tablets (see WARNINGS ). Late Treatment Start patients with contraindications to treatment during the early phase of suspected or definite myocardial infarction, patients who appear not to tolerate the full early treatment, and patients in whom the physician wishes to delay therapy for any other reason on metoprolol tartrate tablets, 100 mg twice daily, as soon as their clinical condition allows. Continue therapy for at least 3 months. Although the efficacy of metoprolol beyond 3 months has not been conclusively established, data from studies with other beta-blockers suggest that treatment should be continued for 1 to 3 years. Special Populations Pediatric Patients No pediatric studies have been performed. The safety and efficacy of metoprolol in pediatric patients have not been established. Renal Impairment No dose adjustment of metoprolol tartrate tablets is required in patients with renal impairment. Hepatic Impairment Metoprolol blood levels are likely to increase substantially in patients with hepatic impairment. Therefore, metoprolol tartrate tablets should be initiated at low doses with cautious gradual dose titration according to clinical response. Geriatric Patients (> 65 Years) In general, use a low initial starting dose in elderly patients given their greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy. Method of Administration For oral treatment, the tablets should be swallowed unchewed with a glass of water. Metoprolol tartrate tablets should always be taken in standardized relation with meals. If the physician asks the patient to take metoprolol tartrate tablets either before breakfast or with breakfast, then the patient should continue taking metoprolol tartrate tablets with the same schedule during the course of therapy.

Hypertension and Angina Metoprolol tartrate tablets are contraindicated in sinus bradycardia, heart block greater than first degree, cardiogenic shock, and overt cardiac failure (see WARNINGS ). Hypersensitivity to metoprolol and related derivatives, or to any of the excipients; hypersensitivity to other beta-blockers (cross-sensitivity between beta-blockers can occur). Sick-sinus syndrome. Severe peripheral arterial circulatory disorders. Myocardial Infarction Metoprolol is contraindicated in patients with a heart rate < 45 beats/min; second- and third-degree heart block; significant first-degree heart block (P-R interval ≥ 0.24 sec); systolic blood pressure < 100 mmHg; or moderate to severe cardiac failure (see WARNINGS ).

Hypertension and Angina Most adverse effects have been mild and transient. Central Nervous System Tiredness and dizziness have occurred in about 10 of 100 patients. Depression has been reported in about 5 of 100 patients. Mental confusion and short-term memory loss have been reported. Headache, nightmares, and insomnia have also been reported. Cardiovascular Shortness of breath and bradycardia have occurred in approximately 3 of 100 patients. Cold extremities; arterial insufficiency, usually of the Raynaud type; palpitations; congestive heart failure; peripheral edema; and hypotension have been reported in about 1 of 100 patients. Gangrene in patients with preexisting severe peripheral circulatory disorders has also been reported very rarely (see CONTRAINDICATIONS , WARNINGS, and PRECAUTIONS ). Respiratory Wheezing (bronchospasm) and dyspnea have been reported in about 1 of 100 patients (see WARNINGS ). Rhinitis has also been reported. Gastrointestinal Diarrhea has occurred in about 5 of 100 patients. Nausea, dry mouth, gastric pain, constipation, flatulence, and heartburn have been reported in about 1 of 100 patients. Vomiting was a common occurrence. Post-marketing experience reveals very rare reports of hepatitis, jaundice and nonspecific hepatic dysfunction. Isolated cases of transaminase, alkaline phosphatase, and lactic dehydrogenase elevations have also been reported. Hypersensitive Reactions Pruritus or rash have occurred in about 5 of 100 patients. Very rarely, photosensitivity and worsening of psoriasis has been reported. Miscellaneous Peyronie’s disease has been reported in fewer than 1 of 100,000 patients. Musculoskeletal pain, blurred vision, and tinnitus have also been reported. There have been rare reports of reversible alopecia, agranulocytosis, and dry eyes. Discontinuation of the drug should be considered if any such reaction is not otherwise explicable. There have been very rare reports of weight gain, arthritis, and retroperitoneal fibrosis (relationship to metoprolol has not been definitely established). The oculomucocutaneous syndrome associated with the beta-blocker practolol has not been reported with metoprolol. Myocardial Infarction Central Nervous System Tiredness has been reported in about 1 of 100 patients. Vertigo, sleep disturbances, hallucinations, headache, dizziness, visual disturbances, confusion, and reduced libido have also been reported, but a drug relationship is not clear. Cardiovascular In the randomized comparison of metoprolol and placebo described in the CLINICAL PHARMACOLOGY section, the following adverse reactions were reported: Metoprolol Tartrate Tablets Placebo Hypotension (systolic BP < 90 mm Hg) 27.4% 23.2% Bradycardia (heart rate < 40 beats/min) 15.9% 6.7% Second- or third-degree heart block 4.7% 4.7% First-degree heart block (P-R ≥ 0.26 sec) 5.3% 1.9% Heart failure 27.5% 29.6% Respiratory Dyspnea of pulmonary origin has been reported in fewer than 1 of 100 patients. Gastrointestinal Nausea and abdominal pain have been reported in fewer than 1 of 100 patients. Dermatologic Rash and worsened psoriasis have been reported, but a drug relationship is not clear. Miscellaneous Unstable diabetes and claudication have been reported, but a drug relationship is not clear. Potential Adverse Reactions A variety of adverse reactions not listed above have been reported with other beta-adrenergic blocking agents and should be considered potential adverse reactions to metoprolol. Central Nervous System Reversible mental depression progressing to catatonia; an acute reversible syndrome characterized by disorientation for time and place, short-term memory loss, emotional lability, slightly clouded sensorium, and decreased performance on neuropsychometrics. Cardiovascular Intensification of AV block (see CONTRAINDICATIONS ). Hematologic Agranulocytosis, nonthrombocytopenic purpura and thrombocytopenic purpura. Hypersensitive Reactions Fever combined with aching and sore throat, laryngospasm and respiratory distress. Post-Marketing Experience The following adverse reactions have been reported during post-approval use of metoprolol: confusional state, an increase in blood triglycerides and a decrease in High Density Lipoprotein (HDL). Because these reports are from a population of uncertain size and are subject to confounding factors, it is not possible to reliably estimate their frequency.

Catecholamine-Depleting Drugs Catecholamine-depleting drugs (e.g., reserpine) may have an additive effect when given with beta-blocking agents or monoamine oxidase (MAO) inhibitors. Observe patients treated with metoprolol plus a catecholamine depletor for evidence of hypotension or marked bradycardia, which may produce vertigo, syncope, or postural hypotension. In addition, possibly significant hypertension may theoretically occur up to 14 days following discontinuation of the concomitant administration with an irreversible MAO inhibitor. Digitalis Glycosides and Beta-Blockers Both digitalis glycosides and beta-blockers slow atrioventricular conduction and decrease heart rate. Concomitant use can increase the risk of bradycardia. Monitor heart rate and PR interval. Calcium Channel Blockers Concomitant administration of a beta-adrenergic antagonist with a calcium channel blocker may produce an additive reduction in myocardial contractility because of negative chronotropic and inotropic effects. CYP2D6 Inhibitors Potent inhibitors of the CYP2D6 enzyme may increase the plasma concentration of metoprolol which would mimic the pharmacokinetics of CYP2D6 poor metabolizer (see CLINICAL PHARMACOLOGY: Pharmacokinetics ). Increase in plasma concentrations of metoprolol would decrease the cardioselectivity of metoprolol. Known clinically significant potent inhibitors of CYP2D6 are antidepressants such as fluvoxamine, fluoxetine, paroxetine, sertraline, bupropion, clomipramine and desipramine; antipsychotics such as chlorpromazine, fluphenazine, haloperidol and thioridazine; antiarrhythmics such as quinidine or propafenone; antiretrovirals such as ritonavir; antihistamines such as diphenhydramine; antimalarials such as hydroxychloroquine or quinidine; antifungals such as terbinafine. Hydralazine Concomitant administration of hydralazine may inhibit presystemic metabolism of metoprolol leading to increased concentrations of metoprolol. Alpha-Adrenergic Agents Antihypertensive effect of alpha-adrenergic blockers such as guanethidine, betanidine, reserpine, alpha-methyldopa or clonidine may be potentiated by beta-blockers including metoprolol. Beta- adrenergic blockers may also potentiate the postural hypotensive effect of the first dose of prazosin, probably by preventing reflex tachycardia. On the contrary, beta-adrenergic blockers may also potentiate the hypertensive response to withdrawal of clonidine in patients receiving concomitant clonidine and beta-adrenergic blocker. If a patient is treated with clonidine and metoprolol concurrently, and clonidine treatment is to be discontinued, stop metoprolol several days before clonidine is withdrawn. Rebound hypertension that can follow withdrawal of clonidine may be increased in patients receiving concurrent beta-blocker treatment. Ergot Alkaloid Concomitant administration with beta-blockers may enhance the vasoconstrictive action of ergot alkaloids. Dipyridamole In general, administration of a beta-blocker should be withheld before dipyridamole testing, with careful monitoring of heart rate following the dipyridamole injection. Carcinogenesis, Mutagenesis, Impairment of Fertility Long-term studies in animals have been conducted to evaluate carcinogenic potential. In a 2-year study in rats at three oral dosage levels of up to 800 mg/kg per day, there was no increase in the development of spontaneously occurring benign or malignant neoplasms of any type. The only histologic changes that appeared to be drug-related were an increased incidence of generally mild focal accumulation of foamy macrophages in pulmonary alveoli and a slight increase in biliary hyperplasia. In a 21-month study in Swiss albino mice at three oral dosage levels of up to 750 mg/kg per day, benign lung tumors (small adenomas) occurred more frequently in female mice receiving the highest dose than in untreated control animals. There was no increase in malignant or total (benign plus malignant) lung tumors, or in the overall incidence of tumors or malignant tumors. This 21-month study was repeated in CD-1 mice, and no statistically or biologically significant differences were observed between treated and control mice of either sex for any type of tumor. All mutagenicity tests performed (a dominant lethal study in mice, chromosome studies in somatic cells, a Salmonella/mammalian-microsome mutagenicity test, and a nucleus anomaly test in somatic interphase nuclei) were negative. Reproduction toxicity studies in mice, rats and rabbits did not indicate teratogenic potential for metoprolol tartrate. Embryotoxicity and/or fetotoxicity in rats and rabbits were noted starting at doses of 50 mg/kg in rats and 25 mg/kg in rabbits, as demonstrated by increases in preimplantation loss, decreases in the number of viable fetuses per dose, and/or decreases in neonatal survival. High doses were associated with some maternal toxicity, and growth delay of the offspring in utero , which was reflected in minimally lower weights at birth. The oral NOAELs for embryo-fetal development in mice, rats, and rabbits were considered to be 25, 200, and 12.5 mg/kg. This corresponds to dose levels that are approximately 0.3 times, 4 times, and 0.5 times, respectively, when based on surface area, the maximum human oral dose (8 mg/kg/day) of metoprolol tartrate. Metoprolol tartrate has been associated with reversible adverse effects on spermatogenesis starting at oral dose levels of 3.5 mg/kg in rats (a dose that is only 0.1 times the human dose, when based on surface area), although other studies have shown no effect of metoprolol tartrate on reproductive performance in male rats. Pregnancy Pregnancy Category C Upon confirming the diagnosis of pregnancy, women should immediately inform their doctor. Metoprolol has been shown to increase postimplantation loss and decrease neonatal survival in rats at doses up to 11 times the maximum daily human dose of 450 mg, when based on surface area. Distribution studies in mice confirm exposure of the fetus when metoprolol is administered to the pregnant animal. These limited animal studies do not indicate direct or indirect harmful effects with respect to teratogenicity (see PRECAUTIONS: Carcinogenesis, Mutagenesis, Impairment of Fertility ). There are no adequate and well controlled studies in pregnant women. The amount of data on the use of metoprolol in pregnant women is limited. The risk to the fetus/mother is unknown. Because animal reproduction studies are not always predictive of human response, this drug should be used during pregnancy only if clearly needed. Nursing Mothers Metoprolol is excreted in breast milk in a very small quantity. An infant consuming one liter of breast milk daily would receive a dose of less than 1 mg of the drug. Fertility The effects of metoprolol on the fertility of human have not been studied. Metoprolol showed effects on spermatogenesis in male rats at a therapeutic dose level, but had no effect on rates of conception at higher doses in animal fertility studies (see PRECAUTIONS: Carcinogenesis, Mutagenesis, Impairment of Fertility ). Pediatric Use Safety and effectiveness in pediatric patients have not been established. Geriatric Use Clinical trials of metoprolol in hypertension did not include sufficient numbers of elderly patients to determine whether patients over 65 years of age differ from younger subjects in their response to metoprolol. Other reported clinical experience in elderly hypertensive patients has not identified any difference in response from younger patients. In worldwide clinical trials of metoprolol in myocardial infarction, where approximately 478 patients were over 65 years of age (0 over 75 years of age), no age related differences in safety and effectiveness were found. Other reported clinical experience in myocardial infarction has not identified differences in response between the elderly and younger patients. However, greater sensitivity of some elderly individuals taking metoprolol cannot be categorically ruled out. Therefore, in general, it is recommended that dosing proceed with caution in this population.